To isolate non-crucial backups from crucial data in the current disk group DATA, a separate new disk group with new disks is needed to put all backups. For meeting our new requirement, we plan to create a disk group called FRA, i.e. Fast Recovery Area, by ourselves. The utility that we are going to use is asmca which is a binary of user grid.
[grid@primary01 ~]$ asmca
Please note that, you have to call asmca by grid, not root.
ASM configuration assistant opened.

Oracle 18c ASMCA
Expand Disk Groups. Then click on Create.

Oracle 18c ASMCA - Disk Groups
Select disk candidates for disk group FRA.

Oracle 18c ASMCA - Create a New Disk Group
The disk group FRA is creating.

Oracle 18c ASMCA - Creating a New Disk Group
The disk group FRA is created.

Oracle 18c ASMCA - a New Disk Group Created